Laboratoire Matière et Systèmes Complexes

October 12th 11h30

The seminar will take place exceptionally in the amphitheatre Pierre Gilles de Gennes. Level -1.

The number of people is limited. Please send an email to Michael Berhanu to attend. There will be also a live diffusion with zoom. Contact Michael Berhanu to attend the video seminar.

Freezing of capillary flows

Axel Huerre, Chargé de recherche CNRS

Laboratoire Matière et Systèmes Complexes (MSC), Université de Paris.

How do ice cascades, stalagmites found in frozen caves in cold regions, or ice circles observed in some frozen rivers form ? The ice structures emerging naturally in cold environments often take on surprising shapes that question scientific curiosity. Here, we are interested in structures formed when a capillary flow is observed on a cold surface. I will present a typical experiment in which a trickle of water flows over a very cold surface. After a few minutes, we notice the formation of an ice wall on which the water flows. We will characterize and explain the dynamics of the formation of the wall and discuss the final shape of the ice structure. In particular, we will be able to identify two distinct regimes. The first is a 1D diffusion regime where the ice grows independently of the flow. In the second, once the ice is thick enough, the heat flux brought by the water becomes important, breaking the symmetry of the problem. The result is a greater thickness of ice downstream. The ice thickness increases linearly and we will explain this phenomenon by considering the balance of heat fluxes between the cold ice and the warm water.

Work performed in collaboration with Antoine Monier (d’Alembert, SU), Thomas Séon (d’Alembert, SU) and Christophe Josserand (LadHyx, Polytechnique)